1. Field of the Invention
The present invention generally relates to a motor casing and, more particularly, to a motor casing that can be coupled with components such as a coil unit or a rotor to form a motor or cooling fan.
2. Description of the Related Art
FIG. 1 shows a conventional motor 8 comprising a motor base 81, a housing 82, a driving assembly 83 and a rotor 84. The motor base 81 comprises a bottom ring 811 which may be coupled by a cover 812. The housing 82 is integrally formed with one end of the bottom ring 811. The driving assembly 83 is disposed in the housing 82 and comprises a coil unit 831 and a circuit board 832 electrically connected to the coil unit 831. The rotor 84 has a shaft 841 rotatably coupled to the housing 82, as well as a permanent magnet 842 located in the housing 82. An air gap is formed between the permanent magnet 842 and the coil unit 831. In such an arrangement, the coil unit 831 may drive the rotor 84 to rotate when the coil unit 831 is electrified to generate magnetic fields interacting with the permanent magnet 842 of the rotor 84.
Generally, the bottom ring 811 of the motor base 81 may be further coupled to a frame 9 via a plurality of ribs 91, and the rotor 84 may form a plurality of vanes 843 on an outer peripheral face thereof. Thus, the frame 9 may be installed in an electronic device. During rotation of the rotor 84, the vanes 843 may guide air through the frame 9 to a certain part of the electronic device where heat is often emitted, attaining cooling purposes of the electronic device.
Since the driving assembly 83 is disposed in the housing 82 and the circuit board 832 has to be electrified to allow the coil unit 831 to generate magnetic fields, the driving assembly 83 will inevitably generate a lot of heat during the operation of the motor 8. However, the motor base 81 is not designed with any structure that allows cooling of the driving assembly 83. For example, the bottom ring 811 merely serves the purposes of supporting the housing 82 or providing connection to the frame 9, and the cover 812 merely serves the purpose of shutting the housing 82. Therefore, the motor base 81 does not provide the driving assembly 83 with a desired cooling mechanism, leading to a difficulty in discharging the heat generated by the driving assembly 83. As a result, the service life of the motor 8 is shortened.